where the first term \(-\pi \mathbb {I}\)  is due to the incompressibility of
the fluid and \(\mathbb {A}_{1}\) , \(\mathbb {A}_{2}\)  are the two first
Rivlin-Ericksen tensors (cf. [1]})
\(\mathbb {A}_{1}(y)=\nabla {y}+\left( \nabla {y}\right) ^{\top }\quad \text{and }\quad \mathbb {A}_{2}(y)=\dot{\mathbb {A}}_{1}(y)+\mathbb {A}_{1}(y)\nabla y+\left( \nabla y\right) ^{\top }\mathbb {A}_{1}(y),\) 
